<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>运算符</title>
    <style>
      div {
        height: 300px;
        background-color: grey;
        text-align: center;
        line-height: 300px;
        font-size: 100px;
      }
      /*@media (max-width: 800px) and (min-width: 700px) {*/
      /*    div {*/
      /*        !* 并且运算符 *!*/
      /*        background-color: orange;*/
      /*    }*/
      /*}*/
      /* 或者运算符 */
      /*@media (max-width: 700px) or (min-width: 800px) {*/
      /*    div {*/
      /*        background-color: skyblue;*/
      /*    }*/
      /*}*/
      /* 否定运算符*/
      /*@media not screen {*/
      /*    div {*/
      /*        background-color: skyblue;*/
      /*    }*/
      /*}*/
      /* 肯定运算符 解决ie不兼容问题 */
      @media only screen {
          div {
              background-color: skyblue;
          }
      }
    </style>
</head>
<body>
  <div>你好啊</div>
</body>
</html>